Date: Tue, 24 Feb 1998 00:32:24 -0500 (EST)
From: Pierce  Nichols <pn30@columbia.edu>
To: GURPSnet-L@io.com
Subject: alternate multi-hull rules


	I find myself vaguely dissatisfied with the rules for multihull
boats as they now stand. Also, they don't take into account that the
primary failure point for a multihull is the wing deck (the part that
connects the hulls). They also tend to have a lot more surface area for a
given volume. Here's a stab at the problem:

	A multi-hull boat is built as a set of three (catamaran) or four
(trimaran) modules. These consist of the hulls and a wing deck. 

	For both: only the hulls have hydrodynamic lines, and only they
need to be waterproof, although waterproofing of the wing deck is *highly*
recommended for sea-going craft. If calculating Hdr using MA Lloyd's
rules, only the surface area of the hulls count. Only the volume of the 
hulls count towards flotation. The HT of the craft is calculated using the
full loaded weight, but *only* the HP of the wing deck. This simulates the
fact that the most common total failure mode for multihulls (other than
capsize) is the wing deck breaking, and a lot of thought is put into the
strengthening of the wing deck. They will often be built with heavier
material than the main hull. 

	For catamaran: The hulls must be the same volume, and the wing
deck must be at least 10% the volume of one hull (i.e. a cat with 100cf
hulls would require a 10cf wing deck). Hl is calculated as in Ve2. Rules
for the sizes of top decks, superstructures, turrets, etc. are as
standard.

	For trimarans: The side hulls may be no more than 50% the volume 
of the center hull. The wing deck must be at least 10% the sum of the
volume of the hulls. Otherwise, it behaves like a catamaran. 

	-p

"A book should be an axe for the frozen sea inside."

	-Franz Kafka

----------------------------------------------------
Addendum (by request of the author):

Hardpoints can be placed under the wing decks; this is useful for
torpedoes, depth charges, etc.  For example, you could design a catamaran
that has a single large hardpoint between the hulls to carry optional
ASW/special ops gear.